System for influencing the rheological properties of a transportable material

ABSTRACT

A system for influencing the rheological properties of a transportable material, especially a free-flowing, pasty or bulk product is associated, or can be associated, with a machine for processing or treating the transportable material in which the transportable material is transported in a transport direction. The system includes at least one controllable operative system for producing mechanical oscillations and applying the same to the material in at least one processing section of the machine, and at least one detection system for detecting the rheological properties of the material. The detected rheological properties are used as a basis for controlling the operative system for producing the mechanical oscillations and applying the same.

BACKGROUND OF THE INVENTION

This invention relates to a system for influencing the rheologicalproperties of a conveyable material, in particular a pourable or pastyproduct or a loose material, wherein the system is or can be allocatedto a machine for machining or processing the conveyable material, inwhich the conveyable material is transported along a conveyingdirection.

A lot of energy and in part correspondingly large machines are requiredfor the transport and machining/processing of viscous or pasty masses,but also for the transport of loose material. In addition, wall frictionduring the transport of such masses or loose material gives rise tovarying retention times of the material in machine areas or in transportlines, which detracts from the quality of the machined/processedmaterial achieved in the end.

U.S. Pat. No. 5,123,433 describes an ultrasound cleaning device and anultrasound cleaning method for a Venturi flow nozzle, through whichstreams a fluid that tends to form deposits. Both a US transmitter andUS receiver are additionally used, wherein the clues as to the thicknessof potential deposits in the nozzle can be gleaned from changes in thereceived US amplitude at a known transmitted US amplitude. Other thanacquiring the state of contamination of the nozzle based on deposits,however, no rheological properties of the streaming fluid are acquired.

SUMMARY OF THE INVENTION

Therefore, the object of the invention is to effect a savings relativeto energy and/or machine size during the machining/processing andprimarily the transport of viscous or pasty materials in the machine onthe one hand, and make it possible to monitor and evaluate therheological properties of the masses in the machine.

This object is achieved according to the invention with a systemmentioned at the outset having the at least one controllable impactsystem for generating and introducing mechanical oscillations in thematerial in at least one machining section of the machine, along with atleast one acquisition system for acquiring the rheological properties ofthe material, wherein the acquired rheological properties are used asthe basis for actuating the impact system for generating and introducingthe mechanical oscillations.

Acquiring the effects of exposure to the at least one controllableimpact system on the rheological properties of the material by means ofthe at least one acquisition system makes it possible to specificallyinfluence the rheological properties in at least one machining area ofthe machine.

According to the invention, the acquisition system preferably has afirst means for determining the velocity field transverse to theconveying direction in an area of the material, and a second means fordetermining the pressure difference along the conveying direction in thearea and/or at the edge of the area of the material, or the acquisitionsystem again has a means for determining the velocity field transverseto the conveying direction in an area of the material, and a secondmeans for determining the shearing stress along the conveying directionat the edge and/or inside the area of the material.

The shearing viscosity function of the material can be determined whenthe velocity field of the material and the pressure difference presenton the material is known, both when using the pressure difference andwhen using the shearing stress. This noninvasive procedure isparticularly well suited for industrial processes.

The system according to the invention can have several impact systemsfor mechanical oscillations, wherein at least one impact system formechanical oscillations can be actuated independently of the operatingstatus. Even several impact systems for mechanical oscillations can beactuated separately from each other. This makes it possible tospecifically influence the material to be processed, machined ortransported, if necessary in a varying manner at different machiningsections of the machine.

In a particularly advantageous embodiment of the system according to theinvention, a first acquisition system for acquiring the rheologicalproperties of the conveyable material is arranged downstream from themachining section in order to generate first signals, which characterizethe physicochemical, in particular rheological properties of thematerial downstream from the machining section. This makes it possibleto continuously monitor the effectiveness of influencing the material inthe machining section, and hence adjust the intensity of influenceexerted as required.

It is best to additionally arrange a second acquisition system foracquiring the rheological properties of the conveyable material upstreamfrom the machining section in order to generate second signals, whichcharacterize the physicochemical, in particular rheological propertiesof the material upstream from the machining section.

The first and second acquisition system now make it possible to comparethe first signals and/or the second signals with respective referencevalues, which characterize specific rheological properties, whereinfeedback takes place within a control circuit as a function of theresult from comparing the signals to activate the at least one impactsystem for mechanical oscillations.

Additionally or alternatively, the first signals and second signals canalso be compared with each other, wherein feedback here also takes placewithin a control circuit as a function of the result from comparing thesignals to activate the at least one impact system for mechanicaloscillations.

Additional advantages, features and possible applications of theinvention will now be presented in the following description ofexemplary embodiments of the invention, which are not to be construed aslimiting

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of the system according to the invention,block diagram;

FIG. 2 is a diagrammatic view of a special embodiment of thecontrollable impact system, longitudinal section along the materialconveying direction; and

FIG. 3 is a diagrammatic view of a special embodiment of the acquisitionsystem, longitudinal section along the material conveying direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a diagrammatic view of the system according to the inventionas a block diagram. A conveyable material whose rheological propertiesare influenced by the system according to the invention flows through amachine section with a casing section G in conveying direction F. Tothis end, a controllable impact system 1 is allocated to the casingsection G of the machine section in the area of a machining section 2 ofthe machine. A first acquisition system 3 and a second acquisitionsystem 4 are allocated to the casing section G downstream and upstreamfrom the processing section (2) of the machine. The first and secondacquisition system 3, 4 are used to acquire the rheological propertiesof the conveyable material downstream and upstream from the machiningsection 2. The first acquisition system 3 is used to generate firstsignals S11, S12, . . . S1n, which characterize the physicochemical, inparticular rheological properties of the material downstream from themachining section 2. The second acquisition system 4 is used to generatesecond signals S21, S22, . . . S2n, which characterize thephysicochemical, in particular rheological properties of the materialupstream from the machining section 2.

The first signals S11, S12, . . . , S1n originating from the firstacquisition system 3 are routed to a closed-loop or open-loop controlcircuit 5. In like manner, the second signals S21, S2, . . . , S2noriginating from the second acquisition system 4 are routed to theclosed-loop or open-loop control circuit 5. The first and second signalsoriginating from the first acquisition system 3 and the secondacquisition system 4 are processed in this closed-loop or open-loopcontrol circuit 5. While processing these signals, for example, thefirst signals S11, S12, . . . , S1n and/or second signals S21, S22, . .. , S2n are compared with respective reference values R11, R12, . . . ,R1n. In addition or as an alternative, the first signals and secondsignals can also be compared to each other. As a function of thecomparison of the first and second signals to the reference values andthe first signals to the second signals, the closed-loop or open-loopcontrol circuit 5 effects an actuation (S31, S32, . . . , S3n) of the ofthe impact system 1, in which the mechanical oscillations necessary forinfluencing the rheological properties of the conveyable material aregenerated.

FIG. 2 is a diagrammatic view of a special embodiment of thecontrollable impact system in a longitudinal section along the materialconveying direction F. A slit die 10 is arranged in the casing sectionG. Along the flowing direction F, the passage area of the slit die 10consists of a tapering inlet area 10 a, which abuts a slit area 10 b,which in turn empties out in an expanding outlet area 10 c. The slit diealso contains a first ultrasound source 11, and is connected with asecond and third ultrasound source 12, 13. The first ultrasound source11 is used to introduce a high-intensity ultrasound wave in the slitarea 10 b, wherein the oscillating direction is predominantlyperpendicular to the flowing direction F. The second and thirdultrasound source 12, 13 are also used to introduce ultrasound waves inthe area of the slit die 10, wherein the oscillating direction runspredominantly parallel to the flowing direction F. A first pressuresensor 14 and second pressure sensor 15 are located at the upstream anddownstream end of the slit area 10 b. The pressure difference betweenthe first pressure sensor 14 and second pressure sensor 15 determined inthis way can be used in conjunction with information about thevolumetric flow through the casing section G to determine the shearingviscosity of the conveyable material M.

FIG. 3 is a diagrammatic view of a special embodiment of the acquisitionsystem in a longitudinal section through the material conveyingdirection F. An ultrasound transmitter/receiver 21 determines thevelocity profile P or velocity of flowing material M from the echo ofthe ultrasound as a function of the radial coordinate. A first pressuresensor 22 upstream from the ultrasound transmitter/receiver and a secondpressure sensor 23 downstream from the ultrasound transmitter/receivermake it possible to determine a pressure difference along the casingwall G, and hence to determine the wall tension. Assuming a linearshearing stress distribution in the tubular cross section, this makes itpossible to determine the shearing viscosity as a function of the localvelocity gradient along with the also determined velocity profile P.

REFERENCE SYMBOL LIST

-   1 Impact system-   2 Machining section-   3 First acquisition system-   4 Second acquisition system-   5 Closed-loop or open-loop control circuit-   10 Slit die-   11 First ultrasound source-   12 Second ultrasound source-   13 Third ultrasound source-   14 First pressure sensor-   15 Second pressure sensor-   10 a Inlet area-   10 b Slit area-   10 c Outlet area-   F Conveying direction-   G Casing section-   P Velocity profile-   M Material-   S11 to S1n First signals-   S21 to S2n Second signals-   R11 to R1n Reference values-   21 Ultrasound transmitter/receiver-   22 First pressure sensor-   23 Second pressure sensor.

1. A system for influencing the rheological properties of a conveyablematerial, wherein the system is or can be allocated to a machine formachining or processing the conveyable material, in which the conveyablematerial is transported along a conveying direction the systemcomprising: a) at least one controllable impact system for generatingand introducing mechanical oscillations in the material in at least onemachining section of the machine, along with b) at least one acquisitionsystem for acquiring the rheological properties of the material; whereinc) the acquired rheological properties are used as the basis foractuating the impact system for generating and introducing themechanical oscillations, d) the acquisition system has a first means fordetermining the velocity field transverse to the conveying direction inan area of the material, and a second means for determining the pressuredifference along the conveying direction in the area and/or at the edgeof the area of the material.
 2. A system for influencing the rheologicalproperties of a conveyable material, wherein the system is or can beallocated to a machine for machining or processing the conveyablematerial, in which the conveyable material is transported along aconveying direction, the system comprising: a) at least one controllableimpact system for generating and introducing mechanical oscillations inthe material in at least one machining section of the machine, alongwith b) at least one acquisition system for acquiring the rheologicalproperties of the material; wherein c) the acquired rheologicalproperties are used as the basis for actuating the impact system forgenerating and introducing the mechanical oscillations, d) theacquisition system has a first means for determining the velocity fieldtransverse to the conveying direction in an area of the material, and asecond means for determining the shearing stress along the conveyingdirection at the edge of or inside the area of the material.
 3. Thesystem according to claims 1 or 2, wherein several impact systems formechanical oscillations are provided.
 4. The system according to claims1 or 2, wherein at least one impact system for mechanical oscillationscan be actuated independently of the operating status of the machine. 5.The system according to claims 1 or 2, wherein several impact systemsfor mechanical oscillations can be actuated separately from each other.6. The system according to claims 1 or 2, wherein a first acquisitionsystem for acquiring the rheological properties of the conveyablematerial is arranged downstream from the machining section in order togenerate first signals, which characterize the physicochemical, inparticular rheological properties of the material downstream from themachining section.
 7. The system according to claim 6, wherein a secondacquisition system for acquiring the rheological properties of theconveyable material is arranged upstream from the machining section inorder to generate second signals, which characterize thephysicochemical, in particular rheological properties of the materialupstream from the machining section.
 8. A machine according to claim 7,wherein the first signals and/or the second signals are compared withrespective reference values, which characterize specific rheologicalproperties, wherein feedback takes place within a control circuit as afunction of the result from comparing the signals to activate the atleast one impact system for mechanical oscillations.
 9. A machineaccording to claim 7, wherein the first signals and/or the secondsignals are compared with each other, wherein feedback takes placewithin a control circuit as a function of the result from comparing thesignals to activate the at least one impact system for mechanicaloscillations.
 10. A system according to claim 1 or 2, wherein theconveyable material comprises a pourable material, a pasty powder or aloose material.